Playtime from PlaytimeHistory's database (SAW_PT_DSN)

A public Playtime tab and player-drawer playtime, and staff-only figures
(who's on, staff activity, disconnect reasons, countries, names, sessions)
for @css/generic on the staff panel and on the public site when signed in.
Hidden unless SAW_PT_DSN is set and its tables are there.

internal/web/admin.go

@@ -245,6 +245,9 @@ func (s *Server) adminPlayer(w http.ResponseWriter, r *http.Request, id *Identit
 	} else if v != nil {
 		resp["verify"] = v
 	}
+	if pt := s.playerPlaytime(r, steamid, s.ptStaff(ctx, id)); pt != nil {
+		resp["playtime"] = pt
+	}
 	writeJSON(w, http.StatusOK, resp)
 }